Hey there

You can take entrance in ISRO as a space scientist by qualifying Indian Institute of space Science Exam Thiruvandrum. Which is done after or during 12th grade. Candidates must have completed bachelor of engineering a bachelor of Technology or equivalent degree.  For more details related to ISRO  you can click on below link:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/isro-recruitment/amp&ved=2ahUKEwiwotb5v4bzAhWAxjgGHZrDChYQFnoECAoQAQ&usg=AOvVaw3nYDvGA2a4zwYsaZdUTUu0&ampcf=1